| Message ID | 20210121151912.4429-1-jeffrey.mitchell@starlab.io (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | xfs: set inode size after creating symlink | expand |
On Thu, Jan 21, 2021 at 09:19:12AM -0600, Jeffrey Mitchell wrote: > When XFS creates a new symlink, it writes its size to disk but not to the > VFS inode. This causes i_size_read() to return 0 for that symlink until > it is re-read from disk, for example when the system is rebooted. > > I found this inconsistency while protecting directories with eCryptFS. Heh. No doubt caused by the fact that we only call i_size_write for regular files, ecryptfs copies i_size_read() of the lower dentry into the ecryptfs inode, and ecryptfs_getattr_link and doesn't call ->getattr on the lower inode. Do directories have the same problem? I'm guessing no because every other file type calls vfs_getattr on the lower dentry, which should link us to xfs_vn_getattr. Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > The command "stat path/to/symlink/in/ecryptfs" will report "Size: 0" if > the symlink was created after the last reboot on an XFS root. > > Call i_size_write() in xfs_symlink() > > Signed-off-by: Jeffrey Mitchell <jeffrey.mitchell@starlab.io> > --- > fs/xfs/xfs_symlink.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c > index 1f43fd7f3209..c835827ae389 100644 > --- a/fs/xfs/xfs_symlink.c > +++ b/fs/xfs/xfs_symlink.c > @@ -300,6 +300,7 @@ xfs_symlink( > } > ASSERT(pathlen == 0); > } > + i_size_write(VFS_I(ip), ip->i_d.di_size); > > /* > * Create the directory entry for the symlink. > -- > 2.25.1 >
On Thu, Jan 21, 2021 at 10:41:37AM -0800, Darrick J. Wong wrote:
> Do directories have the same problem?
Yes, I just checked in a VM. While ecryptfs does call vfs_getattr(), it
only uses the "blocks" value to supplement the data from an identical
generic_fillattr() call to what ecryptfs_getattr_link() uses. The reported
size still comes from i_size_read().
V/R,
Jeffrey Mitchell
On Thu, Jan 21, 2021 at 09:19:12AM -0600, Jeffrey Mitchell wrote: > When XFS creates a new symlink, it writes its size to disk but not to the > VFS inode. This causes i_size_read() to return 0 for that symlink until > it is re-read from disk, for example when the system is rebooted. > > I found this inconsistency while protecting directories with eCryptFS. > The command "stat path/to/symlink/in/ecryptfs" will report "Size: 0" if > the symlink was created after the last reboot on an XFS root. > > Call i_size_write() in xfs_symlink() > > Signed-off-by: Jeffrey Mitchell <jeffrey.mitchell@starlab.io> > --- Reviewed-by: Brian Foster <bfoster@redhat.com> > fs/xfs/xfs_symlink.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c > index 1f43fd7f3209..c835827ae389 100644 > --- a/fs/xfs/xfs_symlink.c > +++ b/fs/xfs/xfs_symlink.c > @@ -300,6 +300,7 @@ xfs_symlink( > } > ASSERT(pathlen == 0); > } > + i_size_write(VFS_I(ip), ip->i_d.di_size); > > /* > * Create the directory entry for the symlink. > -- > 2.25.1 >
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c index 1f43fd7f3209..c835827ae389 100644 --- a/fs/xfs/xfs_symlink.c +++ b/fs/xfs/xfs_symlink.c @@ -300,6 +300,7 @@ xfs_symlink( } ASSERT(pathlen == 0); } + i_size_write(VFS_I(ip), ip->i_d.di_size); /* * Create the directory entry for the symlink.
When XFS creates a new symlink, it writes its size to disk but not to the VFS inode. This causes i_size_read() to return 0 for that symlink until it is re-read from disk, for example when the system is rebooted. I found this inconsistency while protecting directories with eCryptFS. The command "stat path/to/symlink/in/ecryptfs" will report "Size: 0" if the symlink was created after the last reboot on an XFS root. Call i_size_write() in xfs_symlink() Signed-off-by: Jeffrey Mitchell <jeffrey.mitchell@starlab.io> --- fs/xfs/xfs_symlink.c | 1 + 1 file changed, 1 insertion(+)